Publications

morphogenetic interactions occurring between blastemas and stumps after exchanging blastemas between normal and double-half forelimbs in the axolotl, ambystoma mexicanum.		1979	437319
identification by immunofluorescence of prolactin- and somatotropin-producing cells in the pituitary gland of the mexican axolotl (ambystoma mexicanum, shaw).	the indirect immunofluorescence procedure was used to identify prolactin (lth)-and somatotropin (sth)-producing cells in the pituitary of the mexican axolotl. histological staining techniques were employed to corroborate immunocytological results. the lth cells are large, orange-staining cells (acidophils 1) distributed in the posterior two-thirds of the pars distalis. the sth cells are small, erythrosinophilic elements (acidophils 2) principally concentrated in the dorsal part of the pars dista ...	1978	365348
neurotrophic control of the cell cycle during amphibian limb regeneration.	it is shown here that amputated and denervated limbs of larval axolotls dedifferentiate and a proportion of the cells released undergo dna synthesis and mitosis. when the limb is denervated prior to amputation fewer cells go through the cell cycle, implying the existence of a pool of trophic factor in the limb. recent work has demonstrated that denervated blastemal cells accumulate in the g1 phase of the cycle. these results strongly argue against the theory that the trophic factor controls the ...	1978	744947
mesodermalization of amphibian gastrula ectoderm in transfilter experiments.	transfilter experiments were carried out with competent gastrula ectoderm of triturus vulgaris and ambystoma mexicanum as the reacting materials and blastoporal lip, alcohol-treated bone marrow and archenteron roof as the inducing materials, it was shown that a mesodermal inducing substance is able to penetrate nuclepore filters of different pore sizes (3.0, 1.0, 0.4, 0.2 micrometer). the degree of mesodermal differentiations depends on the reacting materials, the inductors and the filters which ...	1978	732366
the effect of healing time on the proximodistal organization of double-half forelimb regenerates in the axolotl, ambystoma mexicanum.		1978	751844
studies on the effects of bleaching amphibian rod pigments. iv. photoresponses recorded intracellularly from axolotl red rods following bleaching flashes.		1978	668824
studies on the effects of bleaching amphibian rod pigments in situ. iii. linear dichroism in axolotl red rods before and during bleaching.		1978	668823
effect of temperature on transplantation immunity in ambystoma mexicanum.	juvenile and mature neotenous ambystoma mexicanum received allogeneic and xenogeneic skin transplants. rejection times for 1st-set, and 3rd-set grafts were noted at 21 degrees c, and for axolotls placed in a cold-room at 7 degrees c 7 h post-grafting, 1 week post-grafting and 2 weeks post-grafting respectively. in all cases graft-rejection was chronic; 2nd and 3rd-set grafts were rejected progressively more rapidly than 1st-set grafts. an important temperature-sensitive event occurs during the 1 ...	1978	357221
the failure of double-half forelimbs to undergo distal transformation following amputation in the axolotl, ambystoma mexicanum.	although capable of initiating early regenerative responses, axolotl forelimb stumps which are composed of double-half limb tissues fail to undergo the events that normally lead to the replacement of missing parts. in the present study, the posterior halves of right forelimbs were exchanged with the anterior halves of left forelimbs, or the dorsal halves of right forelimbs were exchanged with the ventral halves of left forelimbs. forelimbs were amputated through the graft region 30 days after gr ...	1978	660138
supernumerary limbs in the axolotl.		1978	643082
interaction between foreign and regenerating axons in axolotl muscle.		1978	647386
the differentiation-pattern in dependence of the proportion between inducing and induced cells studied on gastrula-ectoderm of ambystoma mexicanum.	the dependence of the differentiation-pattern of competent amphibian ectoderm on the proportion of inducing and induced material was studied. to do so different masses of licl-treated tissue were combined with a constant mass of untreated material. licl-treated isolates corresponding in size with the treated portions in the combinations served as controls. the experiments seem to show at least three factors responsible for the differentiation-pattern of the combinations: the number of inducing c ...	1978	732361
regulation of the mauthner cell following unilateral rotation of the prospective hindbrain in axolotl (ambystoma mexicanum) neurulae.		1978	679039
studies on the effects of bleaching amphibian rod pigments in situ. i. the absorbance spectra of axolotl and tiger salamander rhodopsin and porphyropsin.		1978	639883
a natural heterohaemagglutinin in xenopus laevis serum.	in most adult xenopus laevis the serum contains a 'natural' factor capable of lysing the erythrocytes from a wide variety of amniote species. the factor has no effect on the erythrocytes of another amphibian, ambystoma mexicanum, nor will serum from one animal lyse red cells from another xenopus individual. no lysing factor was present in the serum of larval (tadpole) xenopus. heating of xenopus serum to 56 degrees for 30 min, absorption of the serum with zymosan or inulin, or removal of calcium ...	1978	580428
[effect of valinomycin on mitotic activity and ciliary movement during embryonic development].	the k+ ionophore valinomycin very quickly arrests cleavage in sea urchin and mouse eggs at concentrations ranging between 10 and 3 micron. development of axolotl and xenopus eggs is not arrested before the blastula or gastrula stage. the motility of sea urchin sperm, blastulae and gastrulae is suppressed, within a few minutes, by 1-9 micron valinomycin.	1978	96956
regeneration of mirror symmetrical limbs in the axolotl.	mirrow symmetrical, double posterior limbs were produced by two types of operations on tailbud embryos of the axolotl, ambystoma mexicanum. when the limbs had grown to maturity, they were amputated and a study was made of the structures which regenerated in their place. the majority of the regenerates were also reduplicated, although a significant minority showed other types of symmetry. reduplicate symmetry was often conserved following several amputations, but the number of skeletal elements p ...	1978	667926
developmental studies on an apparent cell-lethal mutant gene-ut-in the mexican axolotl, ambystoma mexicanum.	the discovery of a new mutant gene in stocks of the mexican axolotl derived from breeding stock of the hubrecht laboratory, the netherlands, is described. the gene appears to be a simple recessive and displays complete penetrance. ut/ut larvae develop normally through hatching, but begin to lag in growth and display characteristics defects in gill and limb formation shortly thereafter. the results of parabiosis of normal and mutant embryos, as well as embryological transplants of mutant limb and ...	1978	657276
cinematographical study of cell migration in the opened gastrula of ambystoma mexicanum.	the migration of inner marginal cells was studied in the ambystoma gastrula, using scanning electron micrography and time-lapse cinemicrography. scanning electron micrographs of gastrulae which were fixed while intact revealed that the migrating cells have flattened lamellipodia at their anterior end and a rounded cell body, which can sometimes be seen to be attached to a neighbouring cell by a slender posterior process. films of opened gastrulae showed actively moving cells, with the same featu ...	1978	650142
studies on the effects of bleaching amphibian rod pigments in situ ii. the kinetics of the slow bleaching reactions in axolotl red rods.		1978	639884
experimental studies on a mutant gene, a, causing albinism in the axolotl, ambystoma mexicanum.		1978	414944
the pattern of innervation of a polyneural muscle: axolotl iliotibialis.	the pattern of innervation on individual iliotibialis muscle fibres from axolotl (ambystoma mexicanum) has been investigated histologically and electrophysiologically. these polyneural fibres were found to be innervated on average at five end plate sites. the sites were distributed irregularly along each fibre. average end plate length was found to be approximately 70 micrometer. most end plates were separated by less than 1000 micrometer; 26% by less than 150 micrometer; the average separation ...	1978	627010
[cell proliferation study at various stages of gastrulation in axolotl embryos].	a study of cell proliferation in different regions of axolotl embryos has shown a rather uniform distribution of the s phase and mitotic indices in the animal half of the early and midgastrulae. the dorsal blastoporal lip is characterized by a very low s phase index as compared with the other regions of the embryo.	1978	643249
experimental studies on two mutant genes, r and x, in the mexican axolotl (ambystoma mexicanum).		1978	620874
the occurrence of supernumerary limbs following blastemal transplantation in the regenerating forelimb of the axolotl, ambystoma mexicanum.		1978	620870
myogenesis and inductive processes during heart development in mexican axolotls (ambystoma mexicanum).		1978	367464
distribution and homologies of subunits in the ldh isoenzyme pattern of urodeles.	1. the subunit distribution and homologies of ldh isoenzymes are investigated in the species triturus vulgaris, cristatus, alpestris and helveticus, and ambystoma mexicanum by means of immunoprecipitation and starch gel electrophoresis. 2. fresh tissue extracts contain the following patterns: (a) trit. vulgaris--two isoenzymes: the m4 and h4 tetramers. no hybrid formation is observed between h and m subunits. (b) trit. cristatus--two isoenzymes: the m4 and h4 tetramers. occasional hybrid formati ...	1978	318283
role of thyroid hormones in the normal and glucocorticosteroid hormone-induced evolution of carbamoyl-phosphate synthase (ammonia) activity in axolotl liver.	1. in axolotl liver, the activity of carbamoyl-phosphate synthase (ammonia), expressed per mg liver protein, decreases to a minimum at 5 months of age, then increases to a maximum at 8 months of age which is followed by a decrease again. the initial decrease between 3 and 5 months of age appears to be largely due to an increase in non-carbamoyl-phosphate synthase protein and the following increase between 5 and 8 months of age to a relative increase of carbamoyl-phosphate synthase protein. 2. tr ...	1978	318276
artificial neural induction in amphibia. i. sandwich explants.	1. embryonic tissues (ectoderm, neural plate) of ambystoma mexicanum and tritus were killed with hot water and implanted into ectoderm sandwiches. they induced the ectoderm to form neural tissue, lentoids and unspecialized epidermis. neural tissue always showed retina character. egg pigment was eliminated and gathered at the outer retinal surface or in the centre of rosettes. neural crest cells like mesenchyme or melanophores were completely lacking, retinal pigment did not develop. 2. the thus ...	1977	603082
neuroanatomy of spastic, a behavior mutant of the mexican axoloti: purkinje cell distribution in the adult cerebellum.	the spastic mutant, found in the mexican axolotl, shows swimming coordination and equilibrium deficiencies. histological analyses of wild-type and spastic mutant cerebella previously characterized in physiological studies revealed changes in purkinje cell location in the mutant auricle or vestibulo-cerebellum. purkinje cells are "translocated" ventrally correlated with a similar translocation of vestibular single units described previuosly (ide, '77). where wild-type purkinje cells are distribut ...	1977	915044
neurophysiology of spastic, a behavior mutant of the mexican axoloti: altered vestibular projection to cerebellar auricle and area acoustico-lateralis.	the spastic mutant of ambystoma mexicanum shows deficiencies in swimming coordination and equilibrium. behavior "phenocopy" experiments done previously indicated that vestibular projections to cerebellum and hindbrain interneurons might be responsible for mutant behavior patterns. to test function in mutant vestibular projections, single unit recordings were carried out in the vestibulo-cerebellum (auricle) and hindbrain area acoustico-lateralis (aay) of wild-type and mutant animals in response ...	1977	915043
axolotl stretch reflex [proceedings].		1977	599458
spontaneous release of transmitter from 'repressed' nerve terminals in axolotl muscle.		1977	18677
fiber counts of regenerating peripheral nerves in axolotls and the effect of metamorphosis.	counts have been made of myelinated and unmyelinated fibers in the sixteenth nerve root of the axolotl, before, during and after regeneration following nerve section. there is no loss of myelinated fibers. many collateral sprouts are formed and eventually withdrawn. regeneration during metamorphosis is similar but there is more sprouting. there is no fiber loss from cut nerves in metamorphosis. this suggests that rising thyroid hormone levels are not in themselves detrimental to nerves without p ...	1977	864039
microtubule proteins in axolotl eggs and developing embryos.		1977	559603
on the differentiation of prospective ectoderm to a ciliated cell pattern in embryos of ambystoma mexicanum.	the differentiation of the ectoderm in ambystoma mexicanum (harrison stage 26--27) was examined under in vivo and in vitro conditions by scanning electron microscopy under different experimental conditions. about one out of three flank epidermal cells was found to be ciliated in the undistrubed or control embryos. the shape of ciliated cells in the explants from the animal region was only slightly affected. in no case was it possible to find two adjacent ciliated cells, implying that these cells ...	1977	73569
cardiac mutant salamanders: evidence for heart induction.	homozygosity for gene c in ambystoma mexicanum results in no detectable heartbeat in situ. alteration of the cardiac environment through organ culture results in rapid initiation of spontaneous heartbeat, indicating that absence of cardiac function in situ is not the result of failure of embryonic induction.	1977	908918
a scanning electron microscopic comparison of the development of embryonic and regenerating limbs in the axolotl.	a comparison between the surface features of embryonic limb development and limb regeneration was made in the axolotl. scanning electron microscopy revealed an overall similarity between embryonic and regenerating limbs. a notable feature was the lack of a morphologically discrete apical epidermal specialization on the surface of any of the limbs. histological preparations revealed no thickening of the apical epidermis in embryonic limbs. there is a definite thickening of the apical epidermis in ...	1977	908913
thyroxine-induced gill resorption in the axolotl (ambystoma mexicanum).		1977	903970
dosage effects of the white (d) and melanoid (m) genes on pigment pattern in the mexican axolotl, ambystoma mexicanum, shaw.		1977	892230
[desynchronization of cell division during the early development of the axoloty, loach and salmon].	patterns of a relative measure of asynchrony r of the cell population have been studied by means of a mathematical model of the kinetics of cell population which allows to follow the distribution of cells by the mitotic cycle phases in time. the application of the criterion r for the analysis of the patterns of desynchronization of cell divisions in the early embryogenesis of axolotl, loach and salmon has shown, that, unlike the smooth change of the asynchrony measure in the model populations wi ...	1977	882238
[differentiation behavior of the mesodermal germinal sone of differently old pregastrulation stages of ambystoma mexicanum. cultivation of untreated and lithium-treated isolates].	isolates from the dorsal, lateral and ventral area of the marginal zone are showing differentiation capacities already in the stage of early morula. the composition of the differentiation pattern alters: ecto- and mesodermal tissues are realized until the late morula. beyond these, endodermal structures are visible with the stage of early blastula. after a mild li treatment of the isolates the differentiation pattern of the marginal zone shows significant modifications. ectodermal organs are reg ...	1977	614737
the hormonal regulation of urea excretion in the mexican axoloti (ambystoma mexicanum cope).		1977	188719
control of anteroposterior pattern in the axolotl forelimb by a smoothly graded signal.	(1) it is shown that the number of cartilage elements in an experimentally produced reduplicated limb depends on the width of competent tissue between pieces of flank tissue. (2) seventy well formed reduplications were examined on the assumption that the difference in the number of elements between them results from small differences in graft position. (3) all the reduplications are symmetrical along their entire length. (4) all possess the most posterior structures at both edges with other elem ...	1977	886255
morphological and functional aspects of the arrangement of connective tissue and muscle fibres in the tail of the mexican axolotl, siredon mexicanum (shaw) (amphibia, urodela).	in the lateral musculature of the axolotl tail a multipennate arrangement of muscle fibres is found in the 3rd postanal myomere and all following myomeres. this arrangement appears in larval stages as soon as the myomeres concerned are fully differentiated. within a myomere a uniform degree of contraction of the muscle fibres may be achieved either by helical arrangement as seen in teleosts, by diminishing fibre length in medial direction or by a combination of both phenomena. the relation betwe ...	1977	67739
determination of anteroposterior polarity in the axolotl forelimb by an interaction between limb and flank rudiments.	1. it is shown that the mesoderm in the prospective forelimb-bud of the axolotl embryo is thickened and divided into somatic and splanchnic layers, while that of the flank is thinner and divided. the first sign of the limb-bud itself appears at stage 38. 2. a whole, a half or a third of a limb rudiment can develop into a normal or reduplicated limb when transplanted to the flank. 3. an anterior half of a limb rudiment fails to develop when transplanted to the head but will do so if accompanied b ...	1977	886254
experimental studies on a mutant gene (p) causing premature death of ambystoma mexicanum embryos.	the premature death (p) mutation is a recessive lethal, which, in the homozygous condition, gives rise to a complex of abnormalities. the mutant embryos develop only to stage 37, at which time disintegration of superficial tissue begins. many of the abnormalities observed in sections of the stage-37 mutant embryo are related to its failure to establish a functioning circulatory system, or to the resulting edema and/or ascites that distend the abdomen and flanks. there are, however, abnormalities ...	1977	886253
evidence for abnormal heart induction in cardiac-mutant salamanders (ambystoma mexicanum).	homozygosity for simple recessive gene c in axolotl embryos results in the absence of a heartbeat. gene c alters the morphology of the mutant anterior endoderm - the primary heart inductor.	1977	860120
the development of monamine-containing neurons in the brain and spinal cord of the salamander, ambystoma mexicanum.	the distribution of monoamine-containing neurons in the cns of the developing and adult axolotl, ambystoma mexicanum, has been investigated using the histochemical fluorescence technique of falck and hillarp combined with microspectrofluorimetry. the earliest catecholamine-containing neurons to be detected are located in the ventral ependymal zone of the spinal cord at the time of hatching (stage 41). between stages 43 and 46, catecholamine fluorescence can be detected in neurons in the followin ...	1977	856887
the timing of morphogenetic events in the regenerating forelimb of the axolotl, ambystoma mexicanum.		1977	863102
an autoradiographic study of optic fiber projections from eye grafts in eyeless mutant axolotls.		1977	67046
electrophysiological experiments on the mechanism and accuracy of neuromuscular specificity in the axolotl.	the supracoracoideus muscle of the axolotl shoulder girdle is innervated by two nerves, the supracoracoideus nerve (sc) supplying most of the muscle and the posterior supracoracoideus (psc) supplying the posterior corner. all the muscle fibres are multiply innervated and at the border between the two innervations many muscle fibres, when penetrated by a microelectrode, show junction potentials from both nerves. in such cases one junction potential is often very small, below the threshold for exc ...	1977	19787
development of the sympathetic system in the mexican axolotl, ambystoma mexicanum.		1977	557011
the role of grafted skin in the regeneration of x-irradiated axolotl limbs.		1977	320068
the formation and regression of synapses during the re-innervation of axolotl striated muscles.	1. a study has been made of the formation and regression of synapses formed by spinal nerves 16 and 17 in axolotl hind-limb flexor muscles following the severing of nerve 16, using histological, ultrastructural and electrophysiological techniques. 2. axolotl hind-limb flexor myofibres possessed 'en plaque' end-plates from either spinal nerve 16 or 17 or both at intervals of about 1000 micronm along their length; the myofibre's length constant was about 700 micronm allowing electrophysiological o ...	1977	191597
analysis of spastic: a neurological mutant of the mexican axolotl.		1977	928456
[heat production in the early stages of axolotl growth according to direct and indirect calorimetry findings].	the level of energetic metabolism of the growing axolotls was studied by the methods of direct and indirect calorimetry. just after the hatching the heat production of the larvae calculated by the gas exchange exceeds markedly the level of heat production measured by the calorimeter. during the subsequent growth the level of heat production changes as a transitional process, so that therafter indirect calorimetry gives constantly higher values of energetic metabolism than direct one.	1977	882247
the role of schwann cells in paradoxical regeneration in the axolotl.	the experiments described here examine further the conditions under which paradoxical regeneration occurs and provide support for the hypothesis that a proximal migration of schwann cells is responsible for the phenomenon. when only the hand is shielded from irradiation and the limb is denervated, amputation through the forearm or upper arm sometimes results in regeneration. the effects of variation in the time interval between denervation and amputation, the level of amputation and the method a ...	1977	591863
preferential expression of the maternal allele for alcohol dehydrogenase (adh) in the amphibian hybrid ambystoma mexicanum (axolotl) x ambystoma texanum.		1977	561728
quantitative studies of the reactions to horizontal angular accelerations in axolotls. i. the head-turning reflexes of normal animals.	1. artifically metamorphosed axolotls were exposed to both brief (impulse) and long-lasting horizontal angular accelerations on a turn-table. the animals responded with a head-turning reaction. 2. the general course of the reaction to impulse acceleration was independent of stimulus intensity. the velocity of the head movement first increased to a maximum exponentially and then decreased in a negative exponential manner. stimulus intensity had a linear relationship to the mean maximum velocity a ...	1977	870596
factors influencing ovulation in the mexican axolotl as revealed by induced spawnings.	axolotl females may be induced to spawn by injecting them with small doses of fsh prior to mating. data on the different categories of spawnings obtained by this procedure have established the following points. (1) spawnings of injected females completely without fertile eggs are small (173 eggs average). courtship occurred in some of the matings (spermatophores found) but not in all. spawnings of injected but uninseminated females re-mated with a second (or third) male, not becoming inseminated ...	1977	845578
developmental interactions in the growth and branching of the lateral dendrite of mauthner's cell (ambystoma mexicanum).		1977	838120
quantitive studies of the reactions to horizontal angular accelerations in axolotls. ii. head-turning reflexes in animals with a supernumerary pair of labyrinths.	in axolotls (ambystoma mexicanun) the labyrinths and the associated parts of the medulla were doubled artificially. in these so-called tandem-heads the vestibular afferent fibres from both labyrinths on one side united within the medulla to form common bundles. the head-turning reflexes following impulse acceleration and during long-lasting acceleration were measured quantitatively and compared with those for normal animals. the form and the time-course of the reactions were almost identical in ...	1977	300773
antibody-dependent cellular cytotoxicity in poikilotherms.	51cr-chromate labelled chicken red blood cells, treated with rabbit (anti-chicken red blood cell) serum, are lysed in vitro, in the absence of complement, by spleen cells from xenopus laevis, ambystoma mexicanum or lacerta viridis. optimal conditions for lysis by xenopus spleen cells were determined. the phenomenon seems homologous with antibody-dependent cellular cytotoxicity (adcc) mediated by mammalian or avian k cells. the phylogenetic significance of the finding is discussed.	1977	612470
ketogenesis in vertebrate livers.	1. the hypothesis is advanced that a gluconeogenic organ such as the liver would evolve to oxidise fatty acids as its source of atp for gluconeogenesis. it is also argued that such an organ might, in the light of current knowledge, be expected to be ketogenic. the animals investigated were lamprey, rainbow trout, eel, toad, axolotl, lizard and rat. 2. the respiratory quotients of liver slices from all animals was close to 0.74. ketone bodies were produced from butyrate by all livers excepting th ...	1977	318434
genetic and experimental studies on three associated mutant genes in the mexican axolotl: st (for stasis), mi (for microphthalmic) and h (for hand lethal).	three mutant genes, st, mi, and h, were discovered in an axolotl male received from mexico city. all three are recessive to their normal alleles, and appear to segregate independently. larvae homozygous for st (for stasis) suffer blockage of the circulation at hatching or shortly after, and the majority soon die; any surviving live only a few weeks at most. the mi/mi (microphthalmic) can be identified at the feeding stage. none survives more than a few days. the h/h (hand lethals) live until the ...	1977	925667
ontogeny of ldh-isozymes in mexican axolotl, ambystoma mexicanum by thin-layer isoelectric focusing.	the ontogeny of lactate dehydrogenase (ldh) isozymes in developing mexican axolotl, ambystoma mexicanum was investigated by thin-layer isoelectric focusing in polyacrylamide gel. the isoelectric points (pi values) of the isozymes were determined. the minor components generally remained masked during conventional electrophoresis, but became sharp as isofocusing progressed. we identified in developing eggs and embryos five major ldh isozymes, which could also be traced in the ovarian eggs. all the ...	1976	992242
[participation of irradiated tissues in the formation of limb regenerates in axolotls].		1976	939173
low resistance junctions between mesoderm cells during development of trunk muscles.	1. electrical connexions between mesoderm cells have been examined during the formation of somites in xenopus laevis, bombina orientalis and ambystoma mexicanum. 2. in xenopus the resting potentials of presumptive myotome cells (-65 + 2 mv, s.e. of mean) and somite muscle cells (-65 +/- 0-6 mv s.e. of mean) were 40 mv, greater than dermatome cells (-25 +/- 0-6 mv, s.e. of mean). similar differences were found in bombina and ambystoma. 3. in all three species cells of the dermatome layer of the m ...	1976	1255515
restoration of vision in genetically eyeless axolotls (ambystoma mexicanum).		1976	1082417
on the determination of the dorso-ventral polarity in the amphibian embryo: suppression by lactate of the formation of ruffini's flask-cells.	cells isolated from the vegetal hemisphere of the blastula of ambystoma mexicanum differentiate spontaneously into fibroblast-like cells. similar cells may be formed from animal cells, provided they are induced either by vegetal cells or by li+. we have found that lactate and various inhibitors of rna synthesis suppress the spontaneous cell differentiation. the effect of lactate differs from that of the other agents in so far as lactate must be present before the second day of culture to suppres ...	1976	1003073
apical secretion from taste bud and other epithelial cells in amphibians.	taste buds of the axolotl, ambystoma mexicanum, contain cells, previously undescribed in this species, which have a long apical process, and are similar to the type iii cells of mammalian taste buds, and to the gustatory cells in fish. in the supporting cells, there is evidence of periodic decapitation, in addition to secretion by exocytosis. bilaminar fragments, which are leaf-shaped bodies formed of two dense laminae separated by a lucent gap, protrude from the apical microvilli of the support ...	1976	1086718
[relationship between mitotic phases at different stages of embryonic development of axolotl].	indices and durations of mitotic phases and interphase have been determined in the axolotl embryos at the late blastula, early gastrula and mid-neurula stages. the data obtained suggest that the ratio of mitotic phases changes during embryogenesis and differs in different rudiments of the embryo at the same developmental stage.	1976	934593
the intracellular localization of carbamoyl-phosphate synthase (ammonia) activity in the liver of the mexican axolotl, ambystoma mexicanum (shaw).		1976	183934
retinofugal pathways in normal and albino axolotls.	the retinofugal pathways of normal and albino axolotls have been studied by tracing the transport of radioactive materials after tritiated proline was injected into one eye. the pathways demonstrated by this method include crossed projections to the diencephalon, pretectum, and tectum, and a small component that goes to the midbrain tegmentum in the basal optic root. ipsilaterally, radioactive label was found in all of the same cerebral regions, but in much smaller quantities. although on the ba ...	1976	1276914
[development of gonads transplanted homoplastically in limbs of sexually immature axolotls].	graft development depends on sexual maturation of the host. three successive steps in development of transplants have been demonstrated: somatic growth, gonial division and germinal maturation. sexual maturity occurs earlier in females than in males.	1976	821644
the cell cycle during amphibian limb regeneration.	the duration of the cell cycle in the blastema of regenerating limbs of axolotls has been measured by means of [3h]thymidine pulse labelling and autoradiography. a chase was required to define the pulse period. an average cell cycle at 20 degrees c takes 53 h, s-phase takes 38 h; including parts of mitosis, g1 is 10 h and g2 is 5 h long. the protracted cycle and s-phase are consonant with the large genome in axolotis and other urodeles. the rapidly growing blastema probably contains a steady pop ...	1976	1270529
horizontal cell potentials: dependence on external sodium ion concentration.	the membrane potential of the horizontal cell of the axolotl is highly dependent on the extracellular concentration of sodium. experimental results reported here are consistent with the suggestion that in the dark the receptors release a synaptic transmitter which increases primarily the sodium conductance of the postsynaptic membrane. externally applied aspartate or glutamate depolarizes the horizontal cell membrane and eliminates the light response of the horizontal cell. however, it appears t ...	1976	1251211
irradiation inhibits the regeneration of aneurogenic limbs.	the developing arms of axolotl larvae from the 2-digit stage onward and the aneurogenic arms of surgically denervated larvae maintained in parabiosis are able to regenerate after amputation. such regeneration is uniformly inhibited by local irradiation of the arm, whether innervated or not. this demonstration refutes a recent hypothesis that x-rays interfere with a special activity of nerves required for regeneration, and supports the earlier concept that x-rays act directly on those cells which ...	1976	1262820
topological analysis of the brain stem of the axolotl ambystoma mexicanum.	the ventricular sulcal pattern and the cellular structure of the brain stem of the axolotl ambystoma mexicanum have been studied in transversely cut nissl and bodian stained serial sections. six longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis, the sulcus medianus superior and the sulcus lateralis mesencephali could be distinguished. a seventh groove, the sulcus isthmi, clearly deviates from the overall longi ...	1976	1270610
mitotic activity and nucleic acid precursor incorporation in denervated and innervated limb stumps of axolotl larvae.	mitotic activity and dna and rna precursor incorporation were compared in innervated regenerating limbs and in denervated, non-regenerating limbs on days 8 and 9 post-amputation. innervated limbs had well-developed cone stage blastemas which showed high cellular mitotic indices and h3-thymidine labeling indices of 0.40-0.50 and h3-uridine labeling indices of 0.50-0.75. in contrast, denervated limbs showed dedifferentiated cells distally under thickened wound epithelia, but essentially no mitotic ...	1976	1262816
alterations in resting membrane properties during neural plate stages of development of the nervous system.	1. the mean resting membrane potential of cells in the neural plate of axolotl embryos increases from -25 to -45 mv (maximum values from -35 to -60 mv) when the embryos move from early to mid-neural plate stages of development. 2. increasing the extracellular [k] to 20 mm shortly before the spontaneous increase in resting potential occurs causes neural plate cells to hyperpolarize. 3. a moderate increase in [k]omicron does not hyperpolarize the membrane of neural plate cells at earlier stages or ...	1976	1255516
non-innervated sense organs of the lateral line: development in the regenerating tail of the salamander ambystoma mexicanum.	new lateral organs (neuromasts) are formed in regenerating tails of the larvae of a urodele, the axolotl (ambystoma mexicanum), even in the absence of the lateral line nerve, as confirmed by electron microscopic examination. the non-innervated organs are similar to normal innervated organs. the hair cells are polarized in opposite directions, and despite the lack of nerve endings, contain synaptic bodies, which in normal innervated organs are found in relation to afferent boutons.	1976	1249591
regulation of lactate dehydrogenase (ldh) and alcohol dehydrogenase (adh) synthesis in liver nuclei, following their transfer into oocytes.	the regulatory effect of oocyte cytoplasm on the synthetic activity of transferred somatic cell nuclei was studied using an interspecific hybrid combination of ambystoma texanum and ambystoma mexicanum (axolotl). the enzymes lactate dehydrogenase (ldh) and alcohol dehydrogenase (adh) were used as markers of gene activity. in both species of salamanders, ldh is synthesized in the liver and oocytes, while adh is tissue-specific being synthesized in the liver but not oocytes. both ldh and adh show ...	1976	12194433
[growth of meckel's cartilage in axolotl (urodelean amphibian)].		1976	1070669
regeneration-promoting properties of tribenoside in amblystoma mexicanum.	tribenoside in a dose of 100 mg/kg i.p. significantly accelerates the regeneration of puncture wounds in the caudal membrane of amblystoma mexicanum. a dose of 200 mg/kg exerts a less-pronounced vulnerary effect and is occasionally toxic. tribenoside also stimulates regeneration in this species when added to bath fluid in a concentration of 1:400,000 (exposure for 6 h daily). a concentration of 1:200,000 is less effective and has a slightly irritant effect on the tissue. 14 days after operation, ...	1976	1037626
morphological and biochemical abnormalities in hearts of cardiac mutant salamanders (ambystoma mexicanum).	the effect of homozygosity for recessive gene c in ambystoma mexicanum is the absence of a heartbeat even though initially heart development appears normal. mutant embryos (c/c) are first distinguishable from their normal siblings (+/+;+/c) at stage 34 (7 days after fertilization) when the normals develop contracting hearts. the mutant hearts at this stage, upon gross examination, appear structurally normal but fail to beat. nevertheless, the mutants survive through stage 41, which is about 20 d ...	1976	1034176
[differentiation tendency in mesodermal germ layer. isolation experiments on morula, blastula and gastrula stadia of axolotl (ambystoma mexicanum)].		1976	1024382
[segregation of amphibian cns. analysis of induction process using combination experiments in ambystoma mexicanum].		1976	1023592
satellite cells in the limb musculature of the axolotl.		1976	1016334
a staging system for forelimb regeneration in the axolotl, ambystoma mexicanum.	a staging system has been devised for normal regeneration from the upper arm in the mature axolotl. it consists of seven externally definable stages: (1) wound healing (wh): (2) dedifferentiation (dd); (3) early bud (eb); (4) medium bud (mb); (5) late bud (lb); (6) palette (pal), and (7) digital outgrowth (do). serial histological sections of 38 regenerating limbs were used to correlate gross stages with microscopic events in the regenerative process.	1976	966285
diploid gynogenesis in the mexican axolotl.	gynogenetic diploid axolotls were produced by activating eggs with ultraviolet-inactivated sperm, and then subjecting the activated eggs to heat shock. optimal conditions for ultraviolet inactivation of the sperm, and for suppression of the second meiotic division by heat shock, were established. gynogenetic diploids produced by these procedures included progeny homozygous for recessive alleles carried by a heterozygous mother. gynogenesis could, therefore, be used to uncover new mutations more ...	1976	971806
protein synthesis in lethal nucleocytoplasmic hybrids between the species pleurodeles waltlii michahelles and ambystoma mexicanum shaw (urodele amphibians) obtained by nuclear grafting.	using polyacrylamide gel electrophoresis, proteins stemming from the nucleus of the donor species in nucleocytoplasmic hybrids were determined. the interspecific lethal nucleocytoplasmic hybrids of pleurodeles waltlii and ambystoma mexicanum were studied. the presence of these proteins at the blastula or early gastrula stages attests to the early nuclear control of their synthesis.	1976	965910
thin-layer isoelectric focusing of soluble and insoluble lens extracts from cataractous and normal mexican axolotl (ambystoma mexicanum).		1976	949994
studies of muscle proteins in embryonic myocardial cells of cardiac lethal mutant mexican axolotls (ambystoma mexicanum) by use of heavy meromyosin binding and sodium dodecyl sulfate polyacrylamide gel electrophoresis.	in the mexican axolotl ambystoma mexicanum recessive mutant gene c, by way of abnormal inductive processes from surrounding tissues, results in an absence of embryonic heart function. the lack of contractions in mutant heart cells apparently results from their inability to form normally organized myofibrils, even though a few actin-like (60-a) and myosin-like (150-a) filaments are present. amorphous "proteinaceous" collections are often visible. in the present study, heavy meromyosin (hmm) treat ...	1976	1107335
stretch receptors in urodele limb muscles.	non-encapsulated, fine beaded nerve endings were found histologically on some muscle fibres in a number of limb muscles in newts and axolotls. they were present in newt muscles that had been chronically de-efferented, and in which no efferent activity survived, and were therefore likely to be sensory. they were located only on muscle fibres on or near the outside surface of the muscle. these small-diameter muscle fibres were characterised histochemically by low lipid, sdh and phosphorylase conte ...	1976	129283
how x-rays inhibit amphibian limb regeneration.	the effects of an inhibiting dose of 2,000 rad of x-rays on the regenerating limbs of axolotl larvae have been examined in a histological and cytological study. particular attention was paid to the mitotic indices of normal and irradiated epidermal and blastemal cells. both the characteristic pattern of epidermal mitotic stimulation which normally follows amputation and the later increase in blastemal mitoses are suppressed by irradiation. in most cells the effects are permanent, but in a small ...	1976	939955
[effect of prolactin on mucous epidermal cells in the intact and hypophysectomized axolotl].		1975	54279
proceedings: development of the ipsilateral visual projection in axolotls treated with thyroxine.		1975	1177125
[demonstration of rna synthesis during segmentation in the axolotl embryo].	study of the incorporation of 3h-uridine in cleaving embryo of axolotl has shown a nuclear rna synthesis during the period of synchronous cleavage (6th cycle) as well as after the onset of asynchronous divisions (9th or 10th cycle). in the early development of the axolotl, the extent of the transcription phase looks to be an essential element of the quantitative control of gene activity.	1975	811409